Aet of printing



Dec. 2, 1924.

E. A. KUNZ ART OF PRINTING Filed Feb. I, 1922 Patented Dec. 2, 1924.

UNITED STATES EDWARD A. KUNZ, OF VIILMETTE, ILLINOIS.

ART OF PRINTING.

Application fried February 1, 1922.

To all 107mm it may concern:

Be it known that I, EDWARD A. KUNZ, a citizen of the United States,residing at Wilmette, in the county of (look and State of Illinois, haveinvented certain new and useful Improvements in the Art of Printing, ofwhich the following is a specification.

My invention relates to the art of printing and refers particularly to anew form of matrix and the process of making same by means of whichgreatly superior results are obtained in the printing process.

It is well known that in printing either black or color where eitherflat bed or rotary printing presses are used, much time is consumed bythe operators because they have to resort to certain manipulations ofthe plate and press, technically known as making ready, which consistsof so-called underlaying the plate and overlaying the impressioncylinder. In order to provide an extended life for a half tone printingplate, it has been common practice to provide an underlay or overlaycommonly known as make ready for the purpose of providing a relativelyheavy pressure in the press on the heavy tones, less pressure on theintermediate tones and even less pressure on the lighter tones. Thisprocedure increases the life of a printing plate very materially. Themake ready referred to is, at best, however, very crude, very expensiveand relatively short lived. A ccording to the present invention, themake ready may be dispensed with, or the article forming part of thesubject matter of the present invention may be used as a decidedlyimproved make ready.

According to the present invention, a matrix is provided for applicationto the face of a printing plate, prior to the printing operation saidapplication being made under pressure when. said plate is put into arelatively soft condition, whereby the levels on the half tone dots orprojections of said plate are varied according to their tones. The termmatrix is to be distinguished from the printing plate, make ready.overlay or underlay. he matrix according to the present invention isintended to be squeezed into a printing plate to vary the levels of theprinting dots of said plate in accordance with the tone values ofsaiddots. An object of my in- Serial No. 533,154.

vention is to provide an improved matrix and method of making same foraccomplishing the above purpose.

A further object is to reduce the cost and time required for theprinting operation.

A further object is to improve the quality of the half tone printingparticularly where true tone and intricate delineation are required.

A further object is to provide an improved matrix and method of makingsame which will prolong the life of a printing plate.

Although my invention has a wide field of application it is particularlyuseful in half-tone printing from original plates or electrotypesespecially in multi-color printing where great accuracy is required andwhere it is highly desirable that the great amount of time for themake-ready operation should be cut down to the minimum and that afterthe form or printing plates are properly imposed and registered itshould be possible to start to print in a much shorter time thanheretofore and to print the greatest possible number of clearimpressions before the printing plates show the effect of wear.

I accomplish the results set forth by means of making a matrix, havingthe design reproduced on a sheet of metal or on a sheet of especiallyprepared paper and so treating the matrix that different portions of thedesign are brought to different levels with respect to the main surfaceof the matrix; that is, the portions of the design which are to printwith a light impression, and the portions that are to print with darkerimpressions, will be so treated that when completed I will have anexceed ingly accurate matrix with the surface of the design at differentlevels according to the lightness or darkness of the impression to befinally printed for the different portions of the design. Such a matrixmay housed for a variety of purposes. I

It has heretofore been customary in ma king the so-called overlay orunderlay, to build up the surface which supports the paper or the plateto be printed so that this surface is at difl'erent levels, the higherlevels being designed to force the paper with greater pressure intocontact with the print ing plate at the portionswhich it is desiredshall be printed heaviest, while at the same Jil time the portions ofthe design having the intermediate tones and high lights in the finishedprinted impression are subjected to correspondingly lighter pressure.This result is ordinarily obtained by making an overlay or underlay inwhich pieces of paper are pasted one over the other until the desiredconfiguration is obtained. It will be noted that not only is this anexceedingly time consuming operation, but in the case of an intricatedesign it is impossible to construct an overlay or underlay which willvary the pressure as between the parts to be printed heavier and theparts to be printed lighter except in a very crude manner.

I am also aware that in order to increase the life of a printing plate,it has been proposed to build up a matrix with pieces of paper in asimilar manner as heretofore described and then subject the printingplate to the action of this matrix by means of pressure so that certainportions of the printing plate are forced to a different level fromother portions of the plate, the object being to have the high lights ata somewhat lower level than the portions of the plate which are to printheavier. This operation also is a very crude one on account of theimpossibility of constructing a matrix in this manner which willaccurately follow all the configurations of the design of the plate.

By the use of my improved matrix I not only avoid the great labor whichis entailed in the construction of matrices according to the formersystems, but I also make the nriatrix much more accurate so that by itsuse in the treatment of the printing plate itself, much improvedresult-s are obtained, and if it should be desired to use my improvedmatrix as an underlay or overlay (changing from negative to positive)much improved results over former overlays or underlays will be had.

My invention contemplates the imposing on a metal sheet of a half tonedesign corresponding to the half tone design of the printing plate withwhich it is to cooperate. The half tone design may be imposed on saidmetal sheet by any preferred method, this matter of .imposing the designon the sheet metal being only preparatory to the steps instituting myinvention. I will now proceed to describe a photographic method. ofimposing said design on said metal sheet.

A photographic process by which my matrix is constructed, appliedparticularly to half-tone relief printing, is to photographically printthe design on a metallic matrix plate provided with a sensitized filmaccording to the usual and well known system of making the printingplate. According to the uses to which the matrix is to be applied, itmay be printed directly from the original halftone photographicnegativefrom which the printing plate is made or a second half-tonephotographic plate or film may be made which may be a negative or apositive, and the matrix may be printed from such second photographicplate or film.

The design which is on the face of the printing plate may also bephotographed either in a positive or a negative, reverse or otherwise,and the matrix printed therefrom. The matrix may alsobemade by printingthe design shown on the printing plate directly onto a special paper orother suitable material and treating such paper or material in a mannersimilar to that hereinafter described.

The matrix may be constructed of relatively thin sheet metal, such ascopper or a suitable alloy thereof, or zinc or suitable alloy thereof,which may be suitably etched with acids or the like, according to thewell known system. After the photographic impression has been printed onthe matrix the matrix is developed and fixed and etched according to theusual system, the fixed photographic film still remaining on the surfaceof the matrix. As is well known, in the case of a half-tone plate whichis made by a similar system, the high lights differ from the otherportions of the plate by the fact that the small dots made by thehalf-tone screen are much smaller after the etching operation has beenperformed than the dots which form the heavy or intermediate portions ofthe design, but the surface of all dots, that is, the high lights orshadows as well as the other intermediate tones or values of the plate,are all in the same plane.

The operation performed on the matrix as described up to this point issubstantially the same as is performed on a printing plate according tothe well known system. The next step in the treatment of the matrix isto entirely remove the film on the surface and to then again etch thesurface of the matrix. The result of this second etching to cause theentire surface of the matrix plate to be affected by the etching fluid.If the matrix is a positive, the highlights of the design will contain.very small half-tone dots, the intermediate tones will contain mediumsize dots, and shadows or dark portions will contain large size dots ormay be entirely solid. 'lhesc dots of various sizes will. be affected bythe second etching in different proportions and in such a manner thatthe tops of the small dots are i'naterially lowered; the medium sizedots forming the middle tones will be only partly eaten away, and. theshadows or darkest tones, that is, the portions of the matrix containingthe largest dots or solid surface will hardly be affected at all. On theother hand, if the matrix is a negative, exactly the opposite condilll)lit!) lion would result. After this second etching has progressed for aproper period, the matrix is removed from the etching bath and suitablywashed to stop further etching.

In order to more clearly understand my invention, reference may be madeto the accompanying drawings, in which- Figure 1 represents a verticalsection through a half-tone printing plate, on a greatly magnifiedscale;

Figure 2 represents a similar vertical section through a matrix afterthe first etch ing, this matrix being made positive with reference tothe printing plate shown in Figure 1; and

Figure 3 represents the matrix shown in Figure 2 after the secondetching, the condition of the plate after the first etching being shownin dotted lines.

As shown clearly in Figure 1, the printing plate 10 has a surfaceconsisting of a plurality of dots having their tops all in the sameplane, but these dots are of different areas, according to the characterof printing impression to be made in different parts of the design. Forexample, the very small (lots 11, 11 represent what will be high lightsin the finished printed impression, whereas the larger dots 12, 12represent in termediate tones, and the very large dots 13, 13 and thesolid portion 14 represent the dark tones and heavy shadows.

Similarly in Figure 2, representing the matrix 15 made positive withrespect to the printing plate, the small dots 11 11 represent highlights, the larger dots 12, 12 represent intermediate tones, and thevery large dots 13 13 and the solid portion 14 represent the dark tonesand heavy shadows.

During the first etching of the matrix 15, the sensitive fixed surfacecoating is allowed to remain on the matrix, so that the surface of allthe dots, irrespective of their size, is in the same plane, the dotsdiffering only in size, exactly as in the case of the printing plate.except that the first etching on the matrix is preferably not quite sodeep as in the case of the printing plate, as will be apparent by anexamination of Figures 1 and 2.

After the first etching, the surface coating of: the matrix is removed,and the ma- 1 rix is agaii'i etched, with the result shown in Figure 3.The entire surface of the matrix is affected the various sized dotsbeing reduced in height in inverse proportion to the areas of said dots.the smallest dots being materially reduced in height, the intermediatedots reduced to a less extent and the large dots being hardly affectedat all, whereby an infinite variation in level is provided correspondingto the tone variations in the design. As appears from an inspection ofFigure 3, the relatively sharp half tone dots or projections are reducedto relatively smooth projections or waves of different levelscorresponding to the dots or tones of the design.

In the case of a matrix made negative with respect to the printingplate, it will be apparent that the effect is exactly the opposite fromthat shown in Figures 2 and 3; that is, the dark tones and deep shadows,after the first etching, will be represented by small dots and the highlights by large dots or a solid surface, and after the second etching,levels will vary accordingly.

It will be evident to those skilled in the art that by the use of myinvention the enormous consumption of time in preparing a matrix by theolder systems either to act 7 as an overlay or underlay or for thepurpose of distorting the surface of the printing plate under pressureis materially lessened, while by the absolute accuracy of the matrixmade according to my invention, a much superior quality and far greaterquantity of impressions may 'be taken from a printing plate than hasheretofore been possible, since there is much more accurate relativedemarcation between the high-lights, intermediate tones and shadows ofthe plate than is the case in the prior practice, with the result thatthe blurring which usually takes place after a relatively short use ofthe printing plate does not occur until after a much longer period ofuse when my improved matrix is used.

It will be apparent to those skilled in the art that many changes couldbe made in the details of my invention as I have described the same,without departing from the spirit or scope thereof.

I claim:

1. In the art of printing, the process of making a matrix which consistsin reproducing a design in a coating applied to the surface of saidmatrix, etching the surface of said matrix with a solvent which does notaffect said coating, removing said coating from said matrix, and againetching said matrix, whereby the surface of the latter is brought to aplurality of different levels according to the difi'erent light values.

2. In the art of printing, the process of making a matrix which consistsin reproducing a half-tone design. in a coating applied to the surfaceof said matrix, etching the surface of said matrix with a solvent whichdoes not affect said coating whereby the design is formed in the surfaceof said matrix with a plurality of dots of different sizes but in thesame plane, removing said coating from said matrix, and again etchingsaid matrix, whereby the surfaces of said dots are removed in an amountinversely proportional to the size of said dots.

3. A matrix for squeezing the printing surface of a half tone printingplate. said matrix having thereon a plurality of levels corresponding tothe tones of said half tone plate.

4. A matrix for squeezing the printing surface of a half tone printingplate, said matrix having thereon a pluralit of projections chemicallyreduced in ieight to various levels corresponding to the tone values ofa predetermined half tone design.

5. In the art of printing, the process of making a matrix which consistsin providing a half tone relief on the surface of a metallic plate andtreating said plate surface, whiles same is free of resist, with anetching solvent to bring said surface to a plurality of different levelsaccording to the different tone values.

6. A matrix for squeezing the printing surface of a half tone printingplate, said matrix havin thereon a luralit'v of waves of. variousheights corresponding to the tones a of a predetermined half tonedesign.

7. An article of the printing art for cooperation with a half toneprinting plate comprising a plate having projections at a plurality oflevels in positions corresponding to the dots of a predetermined halftone design.

8. An article of the printing art for cooperation With ahalf toneprinting plate comprising a plate having projections in smooth Wave format a plurality of levels in positions corresponding to the dots of apredetermined half tone design.

Signed at Chicago, Illinois, this 28th day of January, 1922.

EDWARD A. KUNZ.

